Pressure bonding device and method for manufacturing display device

ABSTRACT

According to an aspect, a pressure bonding device is configured to bond, to a plate-like first workpiece having a curved surface part, a plurality of plate-like second workpieces smaller than the first workpiece. The pressure bonding device includes: a vacuum chamber; a stage disposed in the vacuum chamber and having a shape extending along a first surface of the curved surface part of the first workpiece so as to fix the first surface on the stage; and a bonding unit configured to deform an elastic diaphragm by internal pressure and pressure-bond one of the second workpieces to a second surface of the first workpiece. A plurality of the bonding units are disposed facing the stage.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority from Japanese PatentApplication No. 2018-066080 filed on Mar. 29, 2018 and InternationalPatent Application No. PCT/2019/010378 filed on Mar. 13, 2019, theentire contents of which are incorporated herein by reference.

BACKGROUND 1. Technical Field

What is disclosed herein relates to a pressure bonding device and amethod for manufacturing a display device.

2. Description of the Related Art

Widely known are display devices having a curved surface. JapanesePatent Application Laid-open Publication No. 2015-92422, for example,describes a technology that employs a cover glass serving as a frontplate having a curved surface.

Bonding methods for bonding a display panel to a cover glass are broadlyclassified into a method using a roller described in Japanese PatentApplication Laid-open Publication No. 2016-179600 (JP-A-2016-179600) anda method using a diaphragm described in Japanese Patent ApplicationLaid-open Publication No. 2015-79587 (JP-A-2015-79587).

If a plurality of display panels are bonded to one front plate by thetechnology using a roller described in JP-A-2016-179600, the roller ispressed against the curved surface from the end of the display panels,thereby causing difference in the amount of partial elongation in thedisplay panels. As a result, the display quality of the display panelsmay possibly deteriorate.

If a plurality of display panels are attached to a diaphragm and bondedto one front plate by the technology using a diaphragm described inJP-A-2015-79587, the display panel disposed at the center with respectto a convex part or a concave part of the front plate is not pressedagainst the curved surface from the end of the display panel. Bycontrast, the display panels disposed facing the ends of the convex partor the concave part of the front plate are pressed against the curvedsurface from the end of the display panels, thereby causing differencein the amount of partial elongation in the display panels. As a result,the display quality of the display panels may possibly deteriorate.

There is a need for a pressure bonding device that bonds, to aplate-like first workpiece having a curved surface part, a plurality ofplate-like second workpieces smaller than the first workpiece whilereducing difference in the amount of partial elongation generated in thesecond workpieces. There is a need for a method for manufacturing adisplay device that reduces deterioration in display quality of displaypanels.

SUMMARY

According to an aspect, a pressure bonding device is configured to bond,to a plate-like first workpiece having a curved surface part, aplurality of plate-like second workpieces smaller than the firstworkpiece. The pressure bonding device includes: a vacuum chamber; astage disposed in the vacuum chamber and having a shape extending alonga first surface of the curved surface part of the first workpiece so asto fix the first surface on the stage; and a bonding unit configured todeform an elastic diaphragm by internal pressure and pressure-bond oneof the second workpieces to a second surface of the first workpiece. Aplurality of the bonding units are disposed facing the stage.

According to another aspect, a pressure bonding device is configured tobond a plate-like first workpiece having a curved surface part and aplurality of plate-like second workpieces smaller than the firstworkpiece. The pressure bonding device includes: a vacuum chamber; arestriction mechanism configured to restrict the shape of the firstworkpiece; a stage disposed in the vacuum chamber and having a flatsurface against which the first workpiece is pressed by the restrictionmechanism; and a bonding unit configured to deform an elastic diaphragmby internal pressure and pressure-bond one of the second workpieces to asecond surface of the first workpiece. A plurality of the bonding unitsare disposed facing the stage.

According to another aspect, a method for manufacturing a display deviceby bonding, to a translucent front plate having a curved surface part, aplurality of display panels smaller than the front plate, the methodincludes: preparing including attaching the display panels to respectiveelastic diaphragms and attaching the front plate to a stage facing thediaphragms; and pressure-bonding performed after the preparing andincluding deforming the diaphragms by individual pressures andpressure-bonding the display panels to different positions on the frontplate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of a display device according to afirst embodiment;

FIG. 2 is a schematic plan view of the display device according to thefirst embodiment;

FIG. 3 is a configuration diagram of a pressure bonding device accordingto the first embodiment;

FIG. 4 is a configuration diagram for explaining operations of thepressure bonding device according to the first embodiment;

FIG. 5 is a view for explaining a diaphragm of a pressure bonding deviceaccording to a comparative example;

FIG. 6 is a configuration diagram for explaining operations of apressure bonding device according to a first modification of the firstembodiment;

FIG. 7 is a schematic sectional view of a display device according to asecond embodiment;

FIG. 8 is a schematic plan view of the display device according to thesecond embodiment;

FIG. 9 is a configuration diagram of a pressure bonding device accordingto the second embodiment;

FIG. 10 is a configuration diagram for explaining operations of thepressure bonding device according to the second embodiment;

FIG. 11 is a configuration diagram of a pressure bonding deviceaccording to a third embodiment;

FIG. 12 is a schematic sectional view for explaining a restrictionmechanism of the pressure bonding device according to the thirdembodiment;

FIG. 13 is a schematic plan view for explaining the restrictionmechanism of the pressure bonding device according to the thirdembodiment;

FIG. 14 is a schematic sectional view for explaining an operation of therestriction mechanism of the pressure bonding device according to thethird embodiment;

FIG. 15 is a configuration diagram for explaining operations of thepressure bonding device according to the third embodiment; and

FIG. 16 is a configuration diagram of a pressure bonding deviceaccording to a first modification of the third embodiment.

DETAILED DESCRIPTION

Exemplary aspects (embodiments) to embody the present disclosure aredescribed below in greater detail with reference to the accompanyingdrawings. The contents described in the embodiments are not intended tolimit the present disclosure. Components described below includecomponents easily conceivable by those skilled in the art and componentssubstantially identical therewith. Furthermore, the components describedbelow may be appropriately combined. What is disclosed herein is givenby way of example only, and appropriate modifications made withoutdeparting from the spirit of the invention and easily conceivable bythose skilled in the art naturally fall within the scope of thedisclosure. To simplify the explanation, the drawings may possiblyillustrate the width, the thickness, the shape, and other elements ofeach unit more schematically than the actual aspect. These elements,however, are given by way of example only and are not intended to limitinterpretation of the present disclosure. In the present specificationand the figures, components similar to those previously described withreference to previous figures are denoted by the same referencenumerals, and detailed explanation thereof may be appropriately omitted.

First Embodiment

FIG. 1 is a schematic sectional view of a display device according to afirst embodiment. FIG. 2 is a schematic plan view of the display deviceaccording to the first embodiment. FIG. 1 is a sectional view along lineI-I′ of FIG. 2 . As illustrated in FIG. 1 , a display device 3 accordingto the first embodiment includes a front plate 1 and three displaypanels 2. The three display panels 2 are bonded to the front plate 1 ina manner aligned with a gap ΔL illustrated in FIG. 2 interposedtherebetween. The display panel 2 is smaller than the first plate 1 inplanar view.

The front plate 1 is a cover member that protects the display panels 2.The display panels 2 are disposed on one side of the front plate 1 andbonded to the front plate 1 with an adhesive layer, which is notillustrated, interposed therebetween. The front plate 1 has arectangular shape when viewed from the front as illustrated in FIG. 2 ;however, the shape of the front plate 1 is not limited thereto.

As illustrated in FIG. 1 , the front plate 1 is curved as a whole withcurvature R1. The front plate 1 is made of translucent glass orsynthetic resin. Light from the display panel 2 passes through the frontplate 1. A viewer can see video that appears to be displayed on adisplay surface extending along the surface of the front plate 1.

The display panel 2 is a liquid crystal panel or an organic lightemitting diode panel (hereinafter, referred to as an OLED panel), forexample. The liquid crystal panel or the OLED panel may include a touchpanel. If the display panel 2 is a liquid crystal panel, a backlight isprovided to the back side of the display panel 2. The display panel 2includes a first substrate and a second substrate made of glass or thelike and a liquid crystal layer sandwiched between the first substrateand the second substrate.

The display panel 2, for example, has a rectangular shape when viewedfrom the front. The display panel 2 is curved, and both ends of thedisplay panel 2 in one direction are positioned closer to the viewerthan the center in the one direction is when viewed from the viewer.

As illustrated in FIG. 1 , the curvature of the curved surface part ofthe front plate 1 is constant across the entire surface. The frontsurface of the display panel 2 is bonded to a second surface 1R of thefront plate 1.

To manufacture the display device 3 described above, the firstembodiment uses a pressure bonding device 100. FIG. 3 is a configurationdiagram of the pressure bonding device according to the firstembodiment. FIG. 4 is a configuration diagram for explaining operationsof the pressure bonding device according to the first embodiment. Thepressure bonding device 100 includes a vacuum chamber 5, a vacuum source51, a pressure source 34, a stage 10, bonding units 20A, 20B, and 20C, amovable base 60, control valves 31, 32, and 33, pipes 36, 35, 52, and53, and a control device 30.

The vacuum chamber 5 is a container that houses the stage 10, thebonding units 20A, 20B, and 20C, and the movable base 60. The vacuumsource 51 is a pump and exhausts air in the vacuum chamber 5 through thepipe 52 to make the pressure in the vacuum chamber 5 lower than theatmospheric pressure.

The stage 10 is a jig disposed in the vacuum chamber 5 to fix the frontplate 1 in contact with a fixing part 11 extending along the surface ofthe curved surface part. The movable base 60 is a jig for positioningthe bonding units 20A, 20B, and 20C. The gap between the stage 10 andthe movable base 60 can be appropriately changed.

The bonding unit 20A includes a base 21, a sealing member 6, and adiaphragm 4. The sealing member 6 is a member provided on the peripheryof the diaphragm 4 to seal a space 91 between the base 21 and thediaphragm 4.

The space 91 is sealed by the base 21, the sealing member 6, and thediaphragm 4. The pipe 36 is inserted into the space 91.

As illustrated in FIG. 3 , the attachment surface of the base 21 onwhich the diaphragm 4 is attached extends along the tangent to a fixingsurface 11F of the stage 10 facing the bonding unit 20A at the shortestdistance.

The diaphragm 4 is an elastic member. The elastic member is made ofsheet-like synthetic rubber or elastomer having a uniform thickness whenno pressure is applied thereto. The elastic member may be naturalrubber.

The bonding unit 20B includes a base 22, the sealing member 6, and thediaphragm 4. The base 22 of the bonding unit 20B is different in shapefrom the base 21 of the bonding unit 20A. As illustrated in FIG. 3 , theattachment surface of the base 22 on which the diaphragm 4 is attachedinclines in the bonding unit 20B. The angle of inclination of theattachment surface is formed along the tangent to the fixing surface 11Fof the stage 10 facing the bonding unit 20B at the shortest distance.Explanation of the sealing member 6 and the diaphragm 4 of the bondingunit 20B is omitted because they are the same as those of the bondingunit 20A.

A space 92 is sealed by the base 22, the sealing member 6, and thediaphragm 4. The pipe 36 is inserted into the space 92.

The bonding unit 20C includes a base 23, the sealing member 6, and thediaphragm 4. The base 23 of the bonding unit 20C is different in shapefrom the base 21 of the bonding unit 20A. As illustrated in FIG. 3 , theattachment surface of the base 23 on which the diaphragm 4 is attachedinclines in the bonding unit 20C. The angle of inclination of theattachment surface is formed along the tangent to the fixing surface 11Fof the stage 10 facing the bonding unit 20C at the shortest distance.Explanation of the sealing member 6 and the diaphragm 4 of the bondingunit 20C is omitted because they are the same as those of the bondingunit 20A.

A space 93 is sealed by the base 23, the sealing member 6, and thediaphragm 4. The pipe 36 is inserted into the space 93.

The shortest normal distances between the display panels 2 on therespective bonding units 20A, 20B, and 20C and the front plate 1 areequal on the normal line of the fixing surface 11F of the stage 10.

The pressure source 34 is a pump and supplies gas to the spaces 91, 92,and 93 through the pipes 35 and 36. The gas may be air or another gas,such as nitrogen.

When the pressure in the vacuum chamber 5 is reduced, the pressure inthe space between the bonding units 20A, 20B, and 20C and the stage 10is at least reduced.

The control valves 31, 32, and 33 are electromagnetic valves eachincluding a solenoid. The solenoids operate based on instructions fromthe control device 30, thereby switching the control valves 31, 32, and33 between a depressurization state and a pressurization state. Whilethe control valves 31, 32, and 33 have 2-position 3-port specifications,they do not necessarily have the specifications. The control valves 31,32, and 33 may have 3-position 3-port specifications, for example, toselect any one of the depressurization state, a closure state, and thepressurization state.

In the depressurization state, the control valves 31, 32, and 33 couplethe vacuum source 51 to the spaces 91, 92, and 93, respectively, throughtheir corresponding pipes 36 and the pipe 53. In the depressurizationstate, the control valves 31, 32, and 33 supply no gas to the spaces 91,92, and 93, respectively, from the pressure source 34.

In the pressurization state, the control valves 31, 32, and 33 couplethe pressure source 34 and the spaces 91, 92, and 93, respectively,through their corresponding pipes 36 and the pipe 35. In thepressurization state, the control valves 31, 32, and 33 supply gassupplied from the pressure source 34 to the spaces 91, 92, and 93,respectively.

The control device 30 is a computer including at least a centralprocessing unit (CPU) serving as an arithmetic device and a memoryserving as a storage device, for example. The control device 30 executesa computer program using these hardware resources, thereby implementingvarious functions.

Specifically, the control device 30 reads and loads a computer programstored in a predetermined storage unit (not illustrated) on a memory andcauses the CPU to execute instructions included in the computer programloaded on the memory. The control device 30 according to the firstembodiment controls operations of the vacuum source 51 to control thepressure in the vacuum chamber 5. The control device 30 also controlsoperations of the control valves 31, 32, and 33 to control the pressurein the spaces 91, 92, and 93.

The following describes a method for manufacturing a display deviceusing the pressure bonding device 100 described above. At a preparationprocess, the display panels 2 are attached to the respective diaphragms4 in the vacuum chamber 5 with an adhesive layer interposed therebetweenas illustrated in FIG. 3 . The display panels 2 are each provided withan adhesive layer also on the side facing the front plate 1. Theadhesive layer on the diaphragm 4 has adhesion less than that of theadhesive layer facing the front plate 1.

At the preparation process, the front plate 1 is fixed in contact withthe fixing part 11 and attached to the stage 10 with an adhesive layerinterposed therebetween. The front plate 1 may be attached to the stage10 before, after, or simultaneously with attachment of the displaypanels 2 to the respective diaphragms 4.

After the preparation process, a depressurization process is performedto reduce the pressure in the vacuum chamber 5. The control device 30brings the control valves 31, 32, and 33 into the depressurization stateand drives the vacuum source 51 to control the operations of the vacuumsource 51, thereby controlling the pressure in the vacuum chamber 5.

After the pressure in the vacuum chamber 5 is reduced to a predeterminedpressure, a pressure bonding process is performed to bond the displaypanels 2 to the front plate 1. As illustrated in FIG. 4 , the controldevice 30 brings the control valves 31, 32, and 33 into thepressurization state and increases the pressure in the spaces 91, 92,and 93. At the pressure bonding process, pressure difference isgenerated between the pressure in the vacuum chamber 5 and the pressurein the spaces 91, 92, and 93, thereby deforming the diaphragms 4.Consequently, the volume of the spaces 91, 92, and 93 increases.

As a result, the distance between the diaphragms 4 and the fixing part11 of the stage 10 decreases, thereby bringing the display panels 2attached to the respective diaphragms 4 into contact with the frontplate 1.

FIG. 5 is a view for explaining the diaphragm of a pressure bondingdevice according to a comparative example. As illustrated in FIG. 5 , ifa plurality of display panels 2 are attached to the diaphragm 4 andbonded to the front plate 1, the display panel 2 disposed at the centerwith respect to a convex part or a concave part of the front plate 1 isnot pressed against the curved surface from the end of the display panel2. By contrast, the display panels 2 disposed facing the ends of theconvex part or the concave part of the front plate 1 are pressed againstthe curved surface from the end of the display panels 2, thereby eachforming a gap G on one side of the display panel 2. As a result,difference in the amount of partial elongation is generated in thedisplay panels 2 disposed facing the ends of the convex part or theconcave part of the front plate 1. Consequently, the display quality ofthe display panels 2 may possibly deteriorate.

By contrast, as illustrated in FIG. 4 , the display panels 2 (threedisplay panels 2) according to the first embodiment are not pressedagainst the curved surface from the end of the display panels 2. Thedisplay panels 2 are each bonded to the front plate 1 from the centertoward both ends of the display panel 2. Consequently, difference in theamount of partial elongation is generated on both sides of the displaypanel 2 with respect to the center and is cancelled out. As a result,deterioration in display quality of the display panels 2 is reduced.

At the pressure bonding process, the spaces 91, 92, and 93 furtherexpand, thereby bonding the entire surfaces of the three display panels2 to the front plate 1. At a detachment process performed after thepressure bonding process, the control valves 31, 32, and 33 are switchedfrom the pressurization state to the depressurization state so as todetach the diaphragms 4 from the respective display panels 2.Subsequently, the pressure in the vacuum chamber 5 is brought back tothe atmospheric pressure, and the display device 3 illustrated in FIGS.1 and 2 is taken out.

The manufactured display device 3 is mounted on a dashboard of avehicle, for example. The display device 3 has the advantage that thesurface of the display device 3 smoothly fits to the curved interior ofthe vehicle because the surface of the front plate 1 is curved. Thedisplay panels 2 display navigation system, speedometer, tachometer,fuel gauge, and water-temperature gauge, for example.

The display device 3 is not necessarily mounted on a vehicle and may beapplied to other electronic apparatuses, such as portable electronicapparatuses. If the display device 3 is mounted on a vehicle, videodisplayed by the display device 3 is not limited to vehicle gauges andmay be a map of the car navigation system, for example.

The display panel 2 may be an organic EL panel. If the display panel 2is an organic EL panel, no backlight is required. The display panel 2may have a touch detection function. In other words, a touch panel maybe provided in the display panel 2 or on the surface of the displaypanel 2.

The front plate 1 is not necessarily made of glass. The front plate 1may be made of translucent synthetic resin, for example.

As described above, the pressure bonding device 100 includes the vacuumchamber 5, the stage 10, and the bonding units 20A, 20B, and 20C. Thebonding units 20A, 20B, and 20C are disposed facing one stage 10. Thestage 10 is disposed in the vacuum chamber 5 and has a shape extendingalong a first surface 1F of the curved surface part of the front plate 1so as to fix the first surface 1F on the stage 10. The bonding units20A, 20B, and 20C deform the respective elastic diaphragms 4 by internalpressures, thereby each pressure-bonding one display panel 2 to thesecond surface 1R of the front plate 1.

This configuration reduces difference in the amount of partialelongation generated in the display panels 2. The pressure bondingdevice 100 can simultaneously bond a plurality of display panels 2serving as plate-like second workpieces to the front plate 1 serving asa plate-like first workpiece having a curved surface part. Consequently,the display device 3 can be manufactured in a shorter time at a lowercost.

In the method for manufacturing the display device 3 described above,the bonding units 20A, 20B, and 20C bond the respective display panels 2to the front plate 1.

Consequently, the pressure for pressing the display panels 2 can besufficiently applied to the front plate 1. As a result, the displaypanels 2 are stably bonded to the front plate 1, thereby reducingdeterioration in display quality. In addition, the display panels 2 areless likely to come off the front panel 1.

If the display panels 2 are liquid crystal panels, misalignment betweenan array substrate and a counter substrate is prevented because ofreduction in the difference in the amount of partial elongationgenerated in the display panels 2. As a result, deterioration in displayquality is reduced.

First Modification of the First Embodiment

FIG. 6 is a configuration diagram for explaining operations of apressure bonding device according to a first modification of the firstembodiment. In the description of the first modification of the firstembodiment, the same components as those according to the firstembodiment are denoted by the same reference numerals, and detailedexplanation thereof is omitted.

In the same manner as the pressure bonding device according to the firstembodiment, the fixing surface 11F of the stage 10 of the pressurebonding device 100 according to the first modification of the firstembodiment has a curved surface part. The stage 10 according to thefirst modification of the first embodiment has the fixing part 11described in the first embodiment.

Unlike the pressure bonding device according to the first embodiment,the pressure bonding device 100 according to the first modification ofthe first embodiment includes the bonding unit 20A according to thefirst embodiment alone. The bonding unit 20A is attached to the movablebase 60 with a guide mechanism 29 interposed therebetween. The guidemechanism 29 is a linear motion guide mechanism that supports thebonding unit 20A movably in a direction FL and a direction FR oppositeto the direction FL along the longitudinal direction of the front plate1 illustrated in FIG. 6 . In the bonding unit 20A, the display panel 2is attached to the diaphragm 4 with an adhesive layer interposedtherebetween.

A mask 9 is a cushioning material that reduces the force of the bondingunit 20A abutting on the already bonded display panels 2 when aplurality of display panels 2 are bonded to the front plate 1.

With this structure, the first modification of the first embodimentprovides the advantageous effects similar to those of the firstembodiment. In addition, the pressure bonding device 100 according tothe first modification of the first embodiment can bond the displaypanels 2 at desired positions depending on the size of a various kindsof front plate 1.

Second Embodiment

FIG. 7 is a schematic sectional view of a display device according to asecond embodiment. FIG. 8 is a schematic plan view of the display deviceaccording to the second embodiment. FIG. 7 is a sectional view alongline VI-VI′ of FIG. 8 . In the description of the second embodiment, thesame components as those according to the first embodiment are denotedby the same reference numerals, and detailed explanation thereof isomitted.

As illustrated in FIG. 7 , the front plate 1 according to the secondembodiment includes a curved surface part 15 having curvature R2, acurved surface part 16 having curvature R3 different from the curvatureR2, and a coupling part 17 that couples the curved surface part 15 andthe curved surface part 16. In other words, the front plate 1 is curvedsuch that the curved surface part 15 is a convex surface, and the curvedsurface part 16 is a concave surface when viewed from the display panel2, and that the curved surface part 15 is a concave surface, and thecurved surface part 16 is a convex surface when viewed from the viewer.As described above, the front plate 1 has the curved surface parts 15and 16 having different curvatures.

As illustrated in FIGS. 7 and 8 , the display panel 2 is curved. Bothends in one direction of the display panel 2 attached to the curvedsurface part 15 are positioned closer to the viewer than the center inthe one direction is when viewed from the viewer. Both ends in onedirection of the display panel 2 attached to the curved surface part 16are positioned farther away from the viewer than the center in the onedirection is when viewed from the viewer.

FIG. 9 is a configuration diagram of a pressure bonding device accordingto the second embodiment. The stage 10 is a jig disposed in the vacuumchamber 5 to fix the front plate 1 in contact with fixing parts 11 and12 extending along the first surface 1F of the curved surface parts 15and 16. The fixing part 11 has a convex shape protruding from the sidefacing the movable base 60, and the fixing part 12 has a concave shaperecessed from the side facing the movable base 60.

A bonding unit 20D includes a base 24, the sealing member 6, and thediaphragm 4. The bonding unit 20D is different from the bonding unit 20Ain the shape of the base 24. Specifically, the base 24 is thicker thanthe base 21. Explanation of the sealing member 6 and the diaphragm 4 ofthe bonding unit 20D is omitted because they are the same as those ofthe bonding unit 20A.

As illustrated in FIG. 9 , the attachment surface of the base 24 onwhich the diaphragm 4 is attached extends along the tangent to a fixingsurface 12F of the fixing part 12 facing the bonding unit 20D at theshortest distance. The shortest normal distance between the displaypanel 2 on the bonding unit 20A and the front plate 1 on the normal lineof the fixing surface 11F is equal to the shortest normal distancebetween the display panel 2 on the bonding unit 20D and the front plate1 on the normal line of the fixing surface 12F.

A space 94 is sealed by the base 24, the sealing member 6, and thediaphragm 4. The pipe 36 is inserted into the space 94.

The following describes a method for manufacturing a display deviceusing the pressure bonding device 100 described above. At thepreparation process, the display panels 2 are attached to the respectivediaphragms 4 in the vacuum chamber 5 with an adhesive layer interposedtherebetween as illustrated in FIG. 9 . The display panels 2 are eachprovided with an adhesive layer also on the side facing the front plate1. The adhesive layer on the diaphragms 4 has adhesion less than that ofthe adhesive layer facing the front plate 1.

At the preparation process, the front plate 1 is fixed in contact withthe fixing parts 11 and 12 and attached to the stage 10 with an adhesivelayer interposed therebetween. The front plate 1 may be attached to thestage 10 before, after, or simultaneously with attachment of the displaypanels 2 to the respective diaphragms 4.

After the preparation process, the depressurization process is performedto reduce the pressure in the vacuum chamber 5. The control device 30brings the control valves 31 and 32 into the depressurization state anddrives the vacuum source 51 to control the operations of the vacuumsource 51, thereby controlling the pressure in the vacuum chamber 5.

After the pressure in the vacuum chamber 5 is reduced to predeterminedpressure, the pressure bonding process is performed to bond the displaypanels 2 to the front plate 1. As illustrated in FIG. 10 , the controldevice 30 brings the control valves 31 and 32 into the pressurizationstate and increases the pressure in the spaces 91 and 94. At thepressure bonding process, pressure difference is generated between thepressure in the vacuum chamber 5 and the pressure in the spaces 91 and94, thereby deforming the diaphragms 4. Consequently, the volume of thespaces 91 and 94 increases.

As a result, the distance between the diaphragms 4 and the fixing parts11 and 12 of the stage 10 decreases, thereby bringing the display panels2 attached to the respective diaphragms 4 into contact with the frontplate 1.

As illustrated in FIG. 10 , the two display panels 2 according to thesecond embodiment are not pressed against the curved surface from theend of the display panels 2. The display panels 2 are each bonded to thefront plate 1 from the center toward both ends of the display panel 2.Consequently, difference in the amount of partial elongation isgenerated on both sides of the display panel 2 with respect to thecenter and is cancelled out. As a result, deterioration in displayquality of the display panels 2 is reduced.

At the pressure bonding process, the spaces 91 and 94 further expand,thereby bonding the entire surfaces of the two display panels 2 to thefront plate 1. At the detachment process performed after the pressurebonding process, the control valves 31 and 32 are switched from thepressurization state to the depressurization state so as to detach thediaphragms 4 from the respective display panels 2. After the diaphragms4 are detached from the respective display panels 2, the pressure in thevacuum chamber 5 is brought back to the atmospheric pressure, and thedisplay device 3 illustrated in FIGS. 7 and 8 is taken out. As describedabove, the pressure bonding device 100 includes the vacuum chamber 5,the stage 10, and the bonding units 20A and 20D. The stage 10 isdisposed in the vacuum chamber 5 and has a shape extending along thefirst surface 1F of the front plate 1 so as to fix the first surface 1Fon the stage 10. The bonding units 20A and 20D deform the respectiveelastic diaphragms 4 by internal pressures, thereby eachpressure-bonding one display panel 2 to the second surface 1R of thefront plate 1.

This configuration reduces difference in the amount of partialelongation generated in the display panels 2. The pressure bondingdevice 100 can simultaneously bond a plurality of display panels 2serving as the plate-like second workpieces to the front plate 1 servingas the plate-like first workpiece having a curved surface part.Consequently, the display device 3 can be manufactured in a shorter timeat a lower cost.

With the base 21 and the base 24 having different thicknesses, thepressure for pressing the display panels 2 can be sufficiently appliedto the curved surface part 15 and the curved surface part 16 havingdifferent distances from the movable base 60. As a result, the displaypanels 2 can be bonded to the front plate 1 having concave and convexparts. In addition, the display panels 2 are less likely to come off thefront panel 1.

Third Embodiment

FIG. 11 is a configuration diagram of a pressure bonding deviceaccording to a third embodiment. In the description of the thirdembodiment, the same components as those according to the first or thesecond embodiment are denoted by the same reference numerals, anddetailed explanation thereof is omitted.

In the pressure bonding device according to the third embodiment, asurface 10F of the stage 10 is a flat surface. The stage 10 according tothe third embodiment does not have the fixing part 11 described in thefirst embodiment.

The pressure bonding device 100 includes the vacuum chamber 5, thevacuum source 51, the pressure source 34, the stage 10, three bondingunits 20F, the movable base 60, the control valves 31, 32, and 33, thepipes 36, 35, 52, and 53, restriction mechanisms 40, holding members 43,and the control device 30. In the bonding units 20F, the display panels2 are attached to the respective diaphragms 4 with an adhesive layerinterposed therebetween. The restriction mechanism 40 restricts thefront plate 1 such that the curved surface thereof is deformed into aflat surface. FIG. 12 is a schematic sectional view for explaining therestriction mechanism of the pressure bonding device according to thethird embodiment. FIG. 13 is a schematic plan view for explaining therestriction mechanism of the pressure bonding device according to thethird embodiment. FIG. 12 is a sectional view along line XI-XI′ of FIG.13 . FIG. 14 is a schematic sectional view for explaining an operationof the restriction mechanism of the pressure bonding device according tothe third embodiment. FIG. 15 is a configuration diagram for explainingoperations of the pressure bonding device according to the thirdembodiment.

As illustrated in FIGS. 12 and 13 , the restriction mechanisms 40 eachinclude a support pole 42 and a claw 41 attached to the end of thesupport pole 42. The support pole 42 is disposed in a through hole 10Hbored through the stage 10 and is vertically driven by a drive device,such as a motor, which is not illustrated. The claw 41 protrudes fromthe support pole 42 in planar view and has a length long enough to becaught on the end of the front plate 1.

As illustrated in FIGS. 12 and 13 , the holding members 43 have a ringshape and are made of synthetic rubber, elastomer, or the like. Theholding members 43 each pass through respective through holes 10 h boredthrough the stage 10 and hold the front plate 1 on the stage 10 in amanner pressing the front plate 1 toward the stage 10.

The following describes a method for manufacturing a display deviceusing the pressure bonding device 100 according to the third embodiment.

In the depressurization state, the control valves 31, 32, and 33 do notsupply gas supplied from the pressure source 34 through the pipe 35 tothe respective pipes 36. In the depressurization state, the controlvalves 31, 32, and 33 couple the vacuum source 51 and respective spaces96 through the pipes 36 and the pipe 53. In the pressurization state,the control valves 31, 32, and 33 couple the pressure source 34 and therespective spaces 96 through the pipes 36 and the pipe 35. In thepressurization state, the control valves 31, 32, and 33 supply gassupplied from the pressure source 34 to the respective spaces 96.

At the preparation process, the display panels 2 are attached to therespective diaphragms 4 in the vacuum chamber 5 with an adhesive layerinterposed therebetween as illustrated in FIG. 11 . The display panels 2are each provided with an adhesive layer also on the side facing thefront plate 1. The adhesive layer on the diaphragm 4 has adhesion lessthan that of the adhesive layer facing the front plate 1.

At the preparation process, the restriction mechanisms 40 are broughtinto contact with the front plate 1 from above. The front plate 1 isinserted between the holding members 43 and the stage 10.

At a flattening process performed after the preparation process, therestriction mechanisms 40 move downward such that the claws 41illustrated in FIG. 14 come closer to the stage 10. Before thediaphragms 4 are deformed, the display panels 2 serving as the secondworkpieces on the respective bonding units 20F are disposed parallel tothe front plate 1 serving as the first workpiece.

After the flattening process, the depressurization process is performedto reduce the pressure in the vacuum chamber 5. The control device 30brings the control valves 31, 32, and 33 into the depressurization stateand drives the vacuum source 51 to control the operations of the vacuumsource 51, thereby controlling the pressure in the vacuum chamber 5.

After the pressure in the vacuum chamber 5 is reduced to predeterminedpressure, the pressure bonding process is performed to bond the displaypanels 2 to the front plate 1. The control device 30 brings the controlvalves 31, 32, and 33 into the pressurization state and increases thepressure in the spaces 96. At the pressure bonding process, pressuredifference is generated between the pressure in the vacuum chamber 5 andthe pressure in the spaces 96, thereby deforming the diaphragms 4.Consequently, the volume of the spaces 96 increases.

As a result, the distance between the diaphragms 4 and the front plate 1of the stage 10 decreases, thereby bringing the display panels 2attached to the respective diaphragms 4 into contact with the frontplate 1. At this time, the front plate 1 has a flat plate shape.Consequently, as illustrated in FIG. 15 , the display panels 2 (threedisplay panels 2) are not pressed against the curved surface from theend of the display panels 2. At the pressure bonding process, the spaces96 further expand, thereby bonding the entire surfaces of the threedisplay panels 2 to the front plate 1.

At the detachment process performed after the pressure bonding process,the control valve 31 is switched from the pressurization state to thedepressurization state so as to detach the diaphragm 4 from the displaypanel 2. After the diaphragms 4 are detached from the respective displaypanels 2, the restriction mechanisms 40 move upward such that the claws41 move away from the stage 10 as illustrated in FIG. 12 . The shape ofthe front plate 1 is restored by its elasticity, and the curved surfacepart appears. As a result, the display panels 2 are deformed along theshape of the second surface 1R of the front plate 1 corresponding to thecurved surface of the front plate 1. Subsequently, the pressure in thevacuum chamber 5 is brought back to the atmospheric pressure, and thedisplay device 3 illustrated in FIGS. 1 and 2 is taken out.

As described above, the pressure bonding device 100 includes the vacuumchamber 5, the restriction mechanisms 40, the stage 10, and the bondingunits 20F. The restriction mechanisms 40 restrict the shape of the frontplate 1. The stage 10 is disposed in the vacuum chamber 5 and has theflat surface 10F. The front plate 1 is pressed against the stage 10 bythe restriction mechanisms 40. The bonding units 20F deform therespective elastic diaphragms 4 by internal pressures, therebypressure-bonding the respective three display panels 2 to the secondsurface 1R of the front plate 1. The display panel 2 serving as onesecond workpiece is attached to one diaphragm 4, and the bonding units20F are disposed facing the stage 10.

This configuration reduces difference in the amount of partialelongation generated in the display panels 2. The pressure bondingdevice 100 simultaneously bonds a plurality of display panels 2 servingas the plate-like second workpieces to the front plate 1 serving as theplate-like first workpiece having a curved surface part. Consequently,the display device 3 can be manufactured in a shorter time at a lowercost.

Alternatively, the pressure bonding device 100 can deform the diaphragms4 of the respective bonding units 20F one by one, therebypressure-bonding the display panels 2 serving as the second workpiecesto the second surface 1R of the front plate 1 serving as the firstworkpiece.

Deforming the diaphragms 4 one by one can improve accuracy in thebonding positions and reduce deterioration in display quality. Inaddition, difference in the amount of partial elongation generated inthe display panels 2 is reduced.

While the curvature of the curved surface part of the front plate 1 isconstant across the entire surface, for example, the front plate 1 mayhave a plurality of curved surface parts like the second embodiment. Thefront plate 1 may have curved surface parts having different curvatures.The front plate 1 may have a plurality of curved surface parts includingconcave curved surface parts and convex curved surface parts.

As described above, according to the method for manufacturing thedisplay device 3, a plurality of display panels 2 smaller than the frontplate 1 can bonded to the translucent front plate 1 having a curvedsurface part. The method for manufacturing the display device 3 includesthe preparation process, the flattening process, and the pressurebonding process. The preparation process includes attaching the displaypanels 2 to at least one elastic diaphragm 4 and attaching the frontplate 1 to the flat stage 10 facing the diaphragm 4. The flatteningprocess is performed before or after the preparation process andincludes deforming the front plate 1 into a flat plate shape. Thepressure bonding process is performed after the flattening process andincludes deforming the diaphragm 4 by pressure and pressure-bonding thedisplay panels 2 to different positions on the front plate 1.

The pressure for pressing the display panels 2 against the front plate 1is likely to be uniform in the plane because the second surface 1R ofthe front plate 1 is flat. As a result, deterioration in display qualityof the display panels 2 is reduced.

First modification of the third embodiment FIG. 16 is a configurationdiagram of a pressure bonding device according to a first modificationof the third embodiment. In the description of the first modification ofthe third embodiment, the same components as those according to thefirst embodiment, the first modification of the first embodiment, thesecond embodiment, or the third embodiment are denoted by the samereference numerals, and detailed explanation thereof is omitted.

In the same manner as the pressure bonding device according to the thirdembodiment, the surface 10F of the stage 10 is a flat surface in thepressure bonding device 100 according to the first modification of thethird embodiment. The stage 10 according to the first modification ofthe third embodiment does not have the fixing part 11 described in thefirst embodiment.

Unlike the pressure bonding device according to the third embodiment,the pressure bonding device 100 according to the first modification ofthe third embodiment includes one bonding unit 20G having the sameconfiguration as that of the bonding unit 20A according to the firstembodiment. The bonding unit 20G is attached to the movable base 60 withthe guide mechanism 29 interposed therebetween. The guide mechanism 29is a linear motion guide mechanism that supports the bonding unit 20Gmovably in the direction FL and the direction FR opposite to thedirection FL along the longitudinal direction of the front plate 1illustrated in FIG. 16 . In the bonding unit 20G, the display panels 2are attached to the respective diaphragms 4 with an adhesive layerinterposed therebetween.

With this structure, the first modification of the third embodimentprovides the advantageous effects similar to those of the thirdembodiment. In addition, the pressure bonding device 100 according tothe first modification of the third embodiment can bond the displaypanels 2 at desired positions depending on the size of a various kindsof front plate 1.

Out of other advantageous effects provided by the aspects described inthe embodiments above, advantageous effects clearly defined by thedescription in the present specification or appropriately conceivable bythose skilled in the art are naturally provided by the presentdisclosure.

The configuration described above may be provided as the followingaspect:

a method for manufacturing a display device by bonding, to a translucentfront plate having a curved surface part, a plurality of display panelssmaller than the front plate, the method including:

preparing including attaching the display panels to at least one elasticdiaphragm and attaching the front plate to a flat stage facing the atleast one diaphragm;

flattening performed before or after the preparing and includingdeforming the front plate into a flat plate shape; and

pressure-bonding performed after the flattening and including deforminga plurality of the diaphragms by individual pressures andpressure-bonding the display panels to different positions on the frontplate.

What is claimed is:
 1. A pressure bonding device configured to bond, toa plate-like first workpiece having a curved surface part, a pluralityof plate-like second workpieces smaller than the first workpiece, thepressure bonding device comprising: a vacuum chamber; a stage disposedin the vacuum chamber and having a shape extending along a first surfaceof the curved surface part of the first workpiece so as to fix the firstsurface on the stage; and a bonding unit configured to deform an elasticdiaphragm by internal pressure and pressure-bond one of the secondworkpieces to a second surface of the first workpiece, wherein aplurality of the bonding units are disposed facing the stage, the firstworkpiece is a translucent front plate, and the second workpieces aredisplay panels.
 2. The pressure bonding device according to claim 1,wherein the curvature of the curved surface part of the first workpieceis constant across the entire surface.
 3. The pressure bonding deviceaccording to claim 1, wherein the first workpiece has a plurality of thecurved surface parts having different curvatures.
 4. The pressurebonding device according to claim 1, wherein the first workpiece has aplurality of the curved surface parts including a concave curved surfacepart and a convex curved surface part.
 5. The pressure bonding deviceaccording to claim 1, wherein the second workpieces are pressure-bondedto the second surface of the first workpiece by deforming a plurality ofthe diaphragms of the bonding units.
 6. The pressure bonding deviceaccording to claim 1, wherein the second workpieces are pressure-bondedto the second surface of the first workpiece by deforming a plurality ofthe diaphragms of the bonding units one by one.
 7. A pressure bondingdevice configured to bond a plate-like first workpiece having a curvedsurface part and a plurality of plate-like second workpieces smallerthan the first workpiece, the pressure bonding device comprising: avacuum chamber; a restriction mechanism configured to restrict the shapeof the first workpiece; a stage disposed in the vacuum chamber andhaving a flat surface against which the first workpiece is pressed bythe restriction mechanism; and a bonding unit configured to deform anelastic diaphragm by internal pressure and pressure-bond one of thesecond workpieces to a second surface of the first workpiece, wherein aplurality of the bonding units are disposed facing the stage.
 8. Thepressure bonding device according to claim 7, wherein the secondworkpieces are pressure-bonded to the second surface of the firstworkpiece by deforming a plurality of the diaphragms of the bondingunits.
 9. The pressure bonding device according to claim 7, wherein thesecond workpieces are pressure-bonded to the second surface of the firstworkpiece by deforming a plurality of the diaphragms of the bondingunits one by one.
 10. The pressure bonding device according to claim 7,wherein the second workpiece on the bonding unit is disposed parallel tothe first workpiece before the diaphragm is deformed.
 11. The pressurebonding device according to claim 7, wherein the first workpiece is atranslucent front plate, and the second workpieces are display panels.